A207244 Number of 4Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 0 1 0 vertically.

9, 81, 287, 987, 2884, 7165, 17929, 40646, 90602, 196548, 412733, 859077, 1751887, 3532169, 7052859, 13932019, 27335037, 53236611, 103050502, 198448577, 380245761, 725544748, 1379004108, 2611731954, 4930796893, 9281596371

Offset

1,1

Comments

Row 4 of A207242

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 5*a(n-1) -4*a(n-2) -12*a(n-3) +3*a(n-4) +47*a(n-5) -17*a(n-6) -66*a(n-7) -9*a(n-8) +90*a(n-9) +2*a(n-10) -33*a(n-11) +a(n-12) -5*a(n-13) -44*a(n-14) +19*a(n-15) +52*a(n-16) -16*a(n-17) -7*a(n-18) -3*a(n-19) +a(n-20) -18*a(n-21) +17*a(n-22) -2*a(n-23) +2*a(n-24) -3*a(n-25) +3*a(n-26) -3*a(n-27) +a(n-28)

Example

Some solutions for n=4
..0..0..1..0....1..0..0..1....0..1..0..1....1..1..1..1....0..1..0..0
..0..1..0..0....0..1..0..1....0..0..1..0....1..1..1..1....0..0..1..0
..0..1..0..0....1..1..0..1....0..0..1..0....1..1..1..1....0..0..1..0
..0..1..0..0....1..0..0..1....0..0..1..0....0..1..0..1....0..0..1..0

Crossrefs

Sequence in context: A207238 A207496 A208165 * A207064 A207119 A207399

Adjacent sequences: A207241 A207242 A207243 * A207245 A207246 A207247

Keyword

nonn

Author

R. H. Hardin, Feb 16 2012

Status

approved